In the field of television broadcasting, radio-frequency ("RF") spectrum allocations are used to define the manner in which the RF spectrum is to be occupied by the television transmission. By way of example, in the United States, television transmissions are divided into two frequency ranges referred to as very-high-frequency (VHF) and ultra-high-frequency (UHF) regions. The VHF region lies roughly in the frequency range of 40 MHz to 200 MHz, while the UHF region extends from about 470 MHz to almost 1.0 GHz. The precise channel and bandwidth assignments include 68 channels, each occupying 6 Mhz. Each television broadcast station ("television station") occupies one channel on the RF spectrum. These channel allocations, however, vary depending upon the particular television service, i.e., satellite transmission, cable service, and over-the-air broadcasts, used by the viewer and the specific geographic area of service. Moreover, each cable service will generally have its own allocations of channels. The table that relates these television stations to their respective channel allocations for any particular television service is sometimes referred to as a channel map. FIG. 1 illustrates examples of three different channel maps for an over-the-air ("OTA") broadcast, and two cable companies, Cable Co. A and Cable Co. B.
With conventional television technology, a printed program guide having the appropriate channel map must be consulted to determine the channel to which the tuner must be set to receive a particular television station. To facilitate this process for the viewer, commercial remote controllers are available equipped with memory for storing the channel map applicable to the particular television service for a given geographic area. The viewer must first set up the remote controller by keying in the entire channel map from the printed program guide manually. Then, when the viewer keys in a particular television station, the controller accesses the channel mapping memory, converts the television station to the applicable channel, and sets the tuner accordingly.
Recently with the advent of systems to set a video cassette recorder (VCR) for unattended recording by means of code numbers, such as used in a commercial system called VCR PLUS+.TM. or with an onscreen cursor to select programs from a list displayed on the television screen, channel mapping has become a necessity. In these systems, the appropriate channel map must be stored in memory so that when the viewer designates a name of a television station by code number or cursor, the corresponding channel is retrieved from the memory and used to automatically set the tuner.
While these channel mapping features have proven to be a convenient way for programming a VCR, the viewer must still manually enter on the remote controller the entire channel map for the particular television service used by the viewer and the geographic location served. This process increases the complexity of programming the VCR and discourages the use of the unattended recording feature by the viewer.
There have been attempts to automate the process of loading the applicable map into memory. U.S. Pat. No. 4,894,714 to Christis discloses the transmission of a channel map from a television transmitter station as a teletext page. The teletext page is downloaded to a channel mapping memory at the television receivers served by that transmitter. This arrangement requires that each and every cable, satellite, or broadcast service transmit its own channel map which occupies a significant portion of the transmission bandwidth.
Accordingly, there is a current need for a method and apparatus that can reduce the volume of data required to implement the channel mapping function. It is desirable that this method and apparatus be automated, requiring minimal user interface.